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A series of Ce3+ and Tb3+ singly‐ and co‐doped NaBa4(AlB4O9)2Cl3 (NBAC) phosphors have been synthesized via high‐temperature solid state route. The crystal structure, morphology, photoluminescent properties, thermal properties and energy transfer process between Ce3+ and Tb3+ were systematically investigated. The structure refinements indicated that the phosphors based on NBAC crystallized in P42nm polar space group in monoclinic phase. The emission color could be tuned from blue (0.1595, 0.0955) to green (0.2689, 0.4334) via changing the ratio of Ce3+/Tb3+. The energy transfer mechanism of Ce3+/Tb3+ was verified to be dipole–quadrupole interaction via the examination of decay times of Ce3+ based on Dexter's theory. The good thermal stability showed the intensities of Ce3+ at 150°C were about 66.9% and 64.88% in NBAC:0.09Ce3+ and NBAC:0.09Ce3+, 0.07Tb3+ of that at room temperature, and the emission intensities of Tb3+ remained 102.41% in NBAC:0.11Tb3+ and 95.22% in NBAC:0.09Ce3+, 0.07Tb3+ due to the nephelauxetic shielding effect and the highly asymmetric rigid framework structure of NBAC. The maximum external quantum efficiency (EQE) of Ce3+ in NBAC:0.09Ce3+, yTb3+ phosphors could reach 43.38% at y = 0.13. Overall, all the results obtained suggested that NBAC:Ce3+, Tb3+ could be a promising option for n‐UV pumped phosphors. [ABSTRACT FROM AUTHOR]

The bluish-green KBaY(BO):Eu phosphors were prepared by high-temperature solid state reaction method. The photoluminescence properties, concentration quenching and energy transfer as well as the luminescence decays were investigated. The emission spectrum showed a single intensive band centered at 500 nm, which correspond to the 4 f 5 d → 4 f transition of Eu. The optimal concentration for the luminescence of Eu in KBaY(BO):Eu was determined to be 0.03 mol. The critical energy transfer distance was calculated as 21.34 Å. The corresponding concentration quenching mechanism was verified to be a dipole-dipole interaction. And the blue-shift behavior of KBaY(BO):Eu with increasing temperature was analyzed by the configurational coordinate diagram. The results indicate that the KBaY(BO):Eu phosphors have potential applications as an ultraviolet-convertible phosphor due to its effective excitation in the ultraviolet rang. [ABSTRACT FROM AUTHOR]

A series of trivalent rare-earth element ions (europium, terbium, dysprosium) singly- and co-doped strontium yttrium borate phosphors was synthesized via the sol–gel method. The phase formation, luminescence properties, decay times, and energy transfer behaviors from terbium ions to europium ions, the thermal stability, and the Commission Internationale de L’Eclairage coordinates were investigated. Under the excitation of ultraviolet light, the singly doped phosphors exhibited green emission of terbium ions, white emission of dysprosium ions, and red emission of europium ions, respectively. For the terbium and europium ions co-doped strontium yttrium borate samples, a white emission can be realized by blending the doping concentration of terbium and europium ions. The critical distance between terbium and europium ions has been calculated to be about 14.52 Å and the energy transfer from terbium to europium occurred through the dipole–quadrupole interaction. At 150°C, the emission intensity of terbium and europium in the 12 mol% terbium and 14 mol% europium co-doped strontium yttrium borate sample was maintained at about 74% and 87% of their corresponding initial values, respectively, and the dysprosium ions singly doped strontium yttrium borate sample showed about 70% of its initial emission intensity at room temperature. The above results suggested that europium, terbium, dysprosium ions singly- and co-doped strontium yttrium borate phosphors have potential applications as ultraviolet-convertible phosphors. [ABSTRACT FROM AUTHOR]

Utilizing energy transfer process, Ce, Tb co-doped BaZrSiO (BZS) phosphors have been successfully prepared via solid state reaction process. The phase structure, photoluminescence properties, decay curves, thermal stability, and the energy transfer mechanism were investigated in this paper. The critical distance calculated by quenching concentration method was 8.84 Å, and the energy transfer process from Ce to Tb in BZS:Ce/Tb phosphors had been demonstrated to be a resonant type via a dipole-quadrupole mechanism. The emission colors of the phosphors could be tuned from blue (0.1625, 0.1261) to green (0.2979, 0.5473) through the corresponding Ce to Tb energy transfer. Moreover, thermal quenching luminescence results revealed that BZS:Ce, Tb exhibited good thermal stability. The Tb intensity of BZS:0.04Ce, 0.02Tb sample showed about 60.88 % of its initial emission intensity at room temperature. The above results indicate that the phosphors may be potentially used as single-component blue-green emission phosphors for application in light emitting device. [ABSTRACT FROM AUTHOR]

A series of Eu2+ and Tb3+ singly-doped and co-doped Sr3Y2(Si3O9)2 (SYSO) phosphors have been synthesized via a conventional high-temperature solid-state reaction. The crystal structures, photoluminescence properties, fluorescence lifetimes, thermal properties and energy transfer of SYSO:Eu2+,Tb3+ were systematically investigated in detail. Rietveld structure refinement of the obtained phosphors indicated that the SYSO host crystallized in a monoclinic system with the space group C2/c (15) and there are three kinds of cation sites for the doped ions to occupy forming emission centers. The photoluminescence (PL) emission bands of SYSO:xEu2+ show a red-shift tendency with increasing Eu2+ content which should be attributed to more Eu2+ ions entering into Sr2/Y2 and Sr3/Y3 sites from the Sr1/Y1 site. For the co-doped SYSO:Eu2+,Tb3+ samples, tunable colors from cyan to green can be realized by varying the doping concentration of the Tb3+ ions. The intense green emission was realized in the SYSO:Eu2+,Tb3+ phosphors on the basis of the highly efficient energy transfer from Eu2+ to Tb3+ with an efficiency of over 89%. As a result, the emission intensity of SYSO:0.01Eu2+,0.21Tb3+ is about 2.5 times higher than that of SYSO:0.21Tb3+ under 340 nm UV excitation. The energy transfer mechanism from Eu2+ to Tb3+ in the SYSO host was ascribed to the quadrupole–quadrupole interactions. These results indicated that the SYSO:Eu2+,Tb3+ phosphors can act as single-phase green emitting phosphors for possible applications in ultraviolet light-based white light-emitting diodes (w-LEDs). [ABSTRACT FROM AUTHOR]